I have had an interest in using R to create maps for a while now. I recently attended the September Maptime Meetup in Cambridge, MA where Ken Johnson walked the group through creating a slippy map using R and leaflet. The meeting gave me the inital skills I needed to create a basic map using the tools he introduced.
This map shows the locations of National Parks in the U.S. They are roughly split up by type of area, and the user can choose what types are shown on the map.